Download – Pharmokinetics and Anaesthesia

Recommended drug doses are derived from average values in population studies and provide no certainty of response in a specific individual. Elimination half-life at steady state is of limited value in describing the recovery profile of a drug administered for a short period only. Context sensitive half-time provides more useful information under these circumstances. If a drug is given as a constant rate infusion, steady-state concentration will only be achieved after four to five half-lives. Partial pressure largely determines the behaviour of an inhaled drug. For maintenance of anaesthesia, a predictable steady state is easier to achieve with an inhalational agent than an intravenous one.

Fred Roberts*, Dan Freshwater-Turner
*Correspondence Email: coolfred@btinternet.com